Double Trigger
Upgrades (Weapon Upgrades)
A weapon with a double trigger treats one trigger as a "safety," with the second trigger being a hair-trigger that fires when the slightest pressure is applied to it. Weapons of this type can be extremely accurate, since only a small amount of pressure is needed to fire them (reducing the chance of moving the weapon slightly while pulling the trigger), but this takes time and training.
If a character has Careful Shot, he gains a +2 bonus on attacks if he aims with a weapon that has a double trigger (rather than the normal +1 bonus provided by the feat).